1. Field of the Invention
The subject invention is related to mechanical joint packing devices, and more particularly, to a labyrinth sealing device for providing a dynamic seal between a rotating shaft and a bearing housing, and a method of assembling the sealing device.
2. Background of the Related Art
Labyrinth type rotary shaft seals are well known in the art. Typically, these devices include two concentric ring structures which define a rotator and a stator. The rotator is sealing engaged with a rotating shaft, and the stator is sealingly engaged with a bearing housing. Specifically contoured pathways or grooves are formed in the interior surfaces of the seal rings to create a maze or labyrinth extending between the exterior of the bearing housing to the interior of the bearing housing. The labyrinth pathway serves as a hydrodynamic barrier to maintain fluid lubricants within the bearing housing and prevent contaminants from entering the bearing housing. The more elaborate the pathway, the less chance there is that contaminating materials will pass through the structure and into the bearing housing. One way of making a more elaborate pathway is to increase the amount of surface area that must be traversed by contaminating materials, i.e., increase the length of the pathway.
In general, the extent of the surface area of the labyrinth pathway will be limited by the degree of mechanical interlock between the two components of the device upon assembly. If the interlocking contact area between the components is relatively small, there will be less surface area to form a labyrinth pathway therebetween. Conversely, if the interlocking contact area between the two components is relatively large, there will be a greater surface area to form a more elaborate labyrinth pathway between the two components.
An example of a prior art labyrinth sealing device in which there is a low degree of mechanical interlock between the rotator and the stator is disclosed in U.S. Pat. No. 4,466,620 to Orlowski. In the Orlowski device, the rotator is provided with an axially extending annular flange for engaging a complementary axially extending annular recess formed in the stator. An example of a prior art labyrinth sealing device in which there is a high degree of mechanical interlock between the rotator and the stator is disclosed in U.S. Pat. Nos. 5,316,317 and 5,431,414 to Fedorovich et al. This is mechanical interlock is achieved during assembly by initially heating the connective portion of a the stator to expand the diameter thereof. The connective portion of the rotator is then positioned radially inside of the connective portion of the stator. The stator is then permitted to cool to effect the interlock between the two components.
Although the Fedorovich et al. device provides an elaborate labyrinth pathway to prevent contaminants from passing through the structure, its method of assembly is both time consuming and inefficient. Accordingly, there exists a need in the art to provide a labyrinth type rotary shaft seal in which there is a high degree of mechanical interlock between the component parts thereof that can be assembled quickly and efficiently.